Sulcus-Deepening Trochleoplasty With Medial Patellofemoral Ligament Reconstruction: Outcomes at 10 to 20 Years.

BACKGROUND: Recent systematic reviews on the outcomes of sulcus-deepening trochleoplasty with adjuvant medial patellofemoral ligament (MPFL) reconstruction at a follow-up of 2 to 6 years have found that the procedure grants good clinical outcomes with low redislocation rates. However, there is a lack of evidence in the literature regarding mid- and long-term follow-ups. PURPOSE: To evaluate the radiographic and clinical outcomes of thick-flap sulcus-deepening trochleoplasty with MPFL reconstruction at a minimum follow-up of 10 years to assess the signs of patellofemoral arthritis, incidence of recurrent dislocation, and grade of patient satisfaction. STUDY DESIGN: Case series; Level of evidence, 4. METHODS: The authors evaluated a retrospective series of 43 patients (48 knees) who underwent sulcus-deepening trochleoplasty between 2003 and 2013. All patients underwent thick-flap sulcus-deepening trochleoplasty with additional MPFL reconstruction. All patients were assessed at a minimum follow-up of 10 years by an independent clinician who noted any patellar redislocation or reoperations in the operated knee and collected the International Knee Documentation Committee (IKDC), Kujala, and satisfaction scores. Furthermore, a radiographic examination was performed to assess patellar height using the Caton-Deschamps index and patellofemoral arthritis using the Iwano classification. RESULTS: At a mean follow-up of 14.8 ± 2.1 years (range, 10-20 years), 4 patients (4 knees) were lost to follow-up (8.3%). The satisfaction, Kujala, and IKDC scores were 8.2 ± 1.6, 77.5 ± 14.4, and 65.7 ± 13.5, respectively. Only 1 patient reported a traumatic patellar dislocation (2%). Radiographs at the final follow-up were available for 34 knees, which revealed Iwano grade 1 in 14 knees (41%), Iwano grade 2 in 7 knees (21%), and no patellofemoral arthritis in 13 knees (38%). CONCLUSION: Sulcus-deepening trochleoplasty with MPFL reconstruction provides satisfactory results and prevents patellar redislocations with no or minimal patellofemoral arthritis.

Effect of Medial Patellofemoral Complex Reconstruction Technique on Patellofemoral Contact Pressure, Contact Area, and Kinematics.

BACKGROUND: Medial patellofemoral ligament (MPFL) reconstruction is considered by many to be the gold standard to treat lateral patellar instability; however, some investigators have reported good clinical results after isolated medial quadriceps tendon-femoral ligament (MQTFL) reconstruction or a combined MPFL/MQTFL reconstruction. A handful of studies have preliminarily investigated the biomechanical consequences of these various medial patellar stabilizing procedures. Despite this, no existing study has included multiple medial patellofemoral complex (MPFC) reconstructions and assessment of lateral patellar translation at distinct flexion angles. HYPOTHESIS: Combined MPFL/MQTFL reconstruction would restore patellofemoral contact areas, forces, and kinematics closest to the native state compared with isolated reconstruction of the MPFL or MQTFL alone. STUDY DESIGN: Controlled laboratory study. METHODS: Ten adult cadaveric knee specimens were prepared and analyzed under 5 different conditions: (1) intact state, (2) transected MPFC, (3) isolated MPFL reconstruction, (4) isolated MQTFL reconstruction, and (5) combined MPFL/MQTFL reconstruction. Patellar tilt, lateral patellar translation, patellofemoral contact forces, and patellofemoral contact areas were measured in each condition from 0° to 80° through simulated knee flexion using a custom servohydraulic load frame with pressure sensor technology and a motion capture system for kinematic data acquisition. RESULTS: The isolated MPFL, isolated MQTFL, and combined MPFL/MQTFL reconstruction conditions produced significantly less lateral patellar tilt compared with the transected MPFC state (P < .05). No statistically significant differences were found when each reconstruction technique was compared with the intact state in patellar tilt, lateral patellar translation, contact forces, and contact areas. CONCLUSION: All 3 reconstruction techniques (isolated MPFL reconstruction, isolated MQTFL reconstruction, and combined MPFL/MQTFL reconstruction) restored native knee kinematics, contact forces, and contact areas without overconstraint. CLINICAL RELEVANCE: Isolated MPFL reconstruction, isolated MQTFL reconstruction, and combined MPFL/MQTFL reconstruction all restore patellofemoral stability comparable with the intact MPFC state without the overconstraint that could be concerning for increasing risk of patellofemoral arthritis.

Nonanatomical femoral tunnel positioning in isolated MPFL reconstruction is not associated with an increased risk of patellofemoral osteoarthritis after a minimum follow-up of 10 years.

PURPOSE: The association between the prevalence of patellofemoral arthritis (PFA) and femoral tunnel positioning following isolated medial patellofemoral ligament reconstruction (MPFLr) has not been well described. The aim of this study was to analyse the relationship between femoral tunnel positioning and the prevalence of PFA. METHODS: This was a single-centre study of patients undergoing an isolated MPFLr between 2006 and 2011 with a minimum of 10 years of follow-up. Outcomes assessed were the presence of PFA on radiographs, recurrence of instability requiring revision surgery and patient-reported outcomes, including Kujala, Tegner and IKDC scores. Tunnel positioning was assessed on postoperative radiographs using two radiographic methods: Schöttle's point and the grid method to localise the femoral tunnel. Patients were grouped based on tunnel positioning and compared. RESULTS: Fifty patients were analysed at a mean follow-up of 12.4 years. Thirty-three patients (66%) had a femoral tunnel position within 7 mm of Schöttle's point and 39 (78%) within the anatomic quadrant, with the most common location according to the grid method in D4 (28%) and E4 (26%), respectively. Thirty-seven patients (74%) had a satisfactory (>80 versus <80) Kujala score at long-term follow-up. None of the examined tunnel assessment methods demonstrated a significant relationship with Tegner, Kujala or International Knee Documentation Committee scores. Patients with a femoral tunnel position >7 mm outside Schöttle's point or were considered to be in a nonanatomic position were not significantly more likely to result in unsatisfactory Kujala scores at the last follow-up. Tunnel positioning and the other tested parameters were not found to be significantly associated with the development of PFA. CONCLUSION: No correlation between femoral tunnel position and risk of PFA or poor outcomes was observed in patients undergoing isolated MPFLr at long-term follow-up. The impact of femoral tunnel placement on long-term outcomes in patients with PFI may be less significant than originally considered. LEVEL OF EVIDENCE: Level IV.

Short-term Functional Outcomes and Complications of Custom Patellofemoral Arthroplasty.

Background: Patellofemoral arthroplasty (PFA) is a treatment option for isolated patellofemoral arthritis. Custom PFA is an innovative procedure utilizing patient-specific instrumentation. The purpose of this study is to evaluate short-term functional outcomes and complications of the custom PFA in treatment of isolated patellofemoral arthritis. Methods: A retrospective study was conducted to analyze patients who received a PFA operation from a single surgeon. Inclusion criteria were surgical patients from 2012 to 2018 who underwent PFA using a custom prosthesis implant. Knee injury and Osteoarthritis Outcome Score for Joint Replacement (KOOS, JR) and Lower Extremity Functional Scale (LEFS) were collected before and after surgery. Results: A total of 79 patients (94 knees) participated in the study; 55 (69.6%) were women. The median age was 57 at the time of index arthroplasty; 15 patients (30 knees) were bilateral. Follow-up rate was 94%. Median follow-up duration was 3.6 years (2-8.9). Overall prefunctional and postfunctional scores differed significantly for both KOOS, JR and LEFS. Postoperative scores increased for KOOS, JR by 27.5 points, and for LEFS, they increased 26.0 points; P < .001 for both. Complications included 6 reoperations (6.7%) related to PFA: 4 conversions (4.4%) to total knee arthroplasty at a median of 2.5 (1.5-3) years after the index procedure, one vastus medialis oblique advancement (1.1%) secondary to patellar maltracking, and one manipulation under anesthesia (1.1%). Conclusions: Custom PFA in patients with isolated patellofemoral arthritis showed good short-term functional outcomes and low revision rates with very few complications.

Outcomes of isolated patellofemoral arthroplasty.

Osteoarthritis of the patellofemoral compartment can cause significant functional impairment. Isolated patellofemoral osteoarthritis affects greater than 10% of males and females over the age of 60. Patellofemoral arthroplasty (PFA) was developed as a joint-preserving procedure that maintains natural knee kinematics in those with isolated patellofemoral disease. First-generation implants were fraught with complications, a high rate of revision, and early conversion to total knee arthroplasty (TKA). Second-generation implants have demonstrated significant improvements in patient-reported outcome measures, complication rates and implant survivorship. Factors that can affect outcomes include surgical indications, patient selection, and PFA prosthesis design. Modern PFA for isolated patellofemoral osteoarthritis has comparable outcomes to TKA for isolated patellofemoral osteoarthritis. In this article, we discuss the use of PFA, implant design, the indications and factors affecting outcomes, and comparison to TKA.

Severe patellofemoral arthritis does not compromise 6-month post-operative range of motion or function following unicondylar knee arthroplasty.

BACKGROUND: The presence of significant patellofemoral arthritis (PFA) is still considered a contraindication for unicondylar knee arthroplasty (UKA) by many surgeons. The purpose of this study was to determine if the presence of severe PFA at the time of UKA compromised early (< 6 months) post-operative knee range of motion or functional outcomes. METHODS: This retrospective review evaluated unilateral and bilateral UKA (323 patients; 418 knees) between 2015 and 2019. Procedures were grouped by degree of PFA present at the time of surgery, including mild PFA (Group 1; N = 266), moderate to severe PFA (Group 2; N = 101), and severe PFA with lateral compartment bone-on-bone contact (Group 3; N = 51). Knee range of motion and Knee Society Knee (KSS-K) and Function (KSS-F) scores were collected both before and at 6 months following surgery. Group differences were evaluated with Kruskal-Wallis and Chi-square tests for continuous and categorical variables, respectively. Univariate and multivariable logistic regressions were performed to determine influential variables associated with post-operative knee flexion being ≤ 120° and presented as odds ratios (OR) and 95% confidence intervals (CI). RESULTS: Pre-operative flexion was lowest in Group 3 (p = 0.010) with 17.6% of knees having flexion ≤ 120°. Post-operative flexion was lowest in Group 3 (119.1° ± 8.4°, p = 0.003) with 19.6% knees having flexion ≤ 120° compared to 9.8% and 8.9% in Groups 1 and 2, respectively. No significant difference in KSS-F following surgery was found; all three groups demonstrated similar clinical improvement. Increased age (OR 1.089, CI 1.036-1.144; p = 0.001) and body mass index (OR 1.082, CI 1.006-1.163; p = 0.034) were found to be associated with post-operative knee flexion ≤ 120°, while high pre-operative flexion (OR 0.949, CI 0.921-0.978; p = 0.001) was found to be inversely associated with poor knee flexion following surgery. CONCLUSION: Patients with severe PFA demonstrate similar clinical improvement following UKA at 6 months as patients with less severe PFA.

Long-Term clinical results of patellofemoral arthroplasty for isolated patellofemoral osteoarthritis.

OBJECTIVES: The aim of this study was to explore the clinical outcomes and long-term survival of patellofemoral arthroplasty in treatment of isolated patellofemoral osteoarthritis. METHODS: We retrospectively studied a total of 46 type Y-L-Q PFAs that were designed at our institution in 38 patients. Implant survivorship was analyzed with a follow-up of 18.9-29.6 years. Knee Society Score (KSS), Oxford Knee Score (OKS), and University of California Los Angeles activity scale (UCLA) were used to assess functional outcomes. RESULTS: The implant survivorship was 83.6% at 15 years, 76.8% at 20 years, and 59.4% at 25 years 14 PFAs in 12 patients were revised into total knee arthroplasty at 16.0 ± 6.7 years; 13 for progression of tibiofemoral osteoarthritis and one for polyethylene wear. The mean Knee Society Score objective scores and functional scores were 73.0 ± 17.5 (range, 49-95) and 56.4 ± 28.9 (range, 5-90), respectively. The mean Oxford Knee Score was 25.8 ± 11.5 (range, 8-44). CONCLUSION: Type Y-L-Q patellofemoral arthroplasty can be an effective method for treating isolated patellofemoral osteoarthritis with satisfactory survival.

Microstructural changes of cartilage and subchondral bone in a guinea pig model of early- and middle-stage patellofemoral arthritis.

OBJECTIVE: Patellofemoral arthritis is a common type of knee osteoarthritis and a prime cause of anterior knee pain and disability. Most of the existing research on knee osteoarthritis focuses on tibial-femoral arthritis, while studies on patellofemoral arthritis are relatively rare. This study aims to observe changes in osteochondral and subchondral bone structure over time in the patella and femoral trochlea in an animal model of spontaneous patellofemoral arthritis. METHODS: A total of 24 1-, 3- or 5-month-old healthy female Hartley guinea pigs were used for experiments. No intervention was applied, and the mechanical pain threshold was assessed prior to euthanasia. Bilateral knee joints were collected in the animals at the different ages, and the patellofemoral joints were taken to evaluate the bone microstructure of patellofemoral articular cartilage and subchondral bone by macroscopy, histopathology and micro-computed tomography (micro-CT). RESULTS: There was a significant difference in the severity of femoral trochlea injury assessed by the Macro score between 5- and 1-month-old groups (P<0.01), as well as in patellar cartilage damage (P<0.05). The mechanical pain threshold of lower extremities in each group was statistically different between different age groups (P<0.05). The OARSI articular cartilage histopathological scores, including patella and femoral trochlea, were significantly different among 1-, 3- and 5-month-old groups. The 5-month-old group exhibited statistically lower values of bone volume/trabecular volume, trabecular number and trabecular thickness in the femoral subchondral bone and evidently higher structure model index than the 1-month-old group. CONCLUSIONS: This study demonstrated that 3- to 5-month-old female Hartley guinea pigs can develop early-to-mid-stage spontaneous patellofemoral arthritis that causes significant cartilage degeneration and loss of subchondral bone. In addition, the bone microarchitecture of the femur is more severely degraded.

Complications and costs of patellofemoral arthroplasty versus total knee arthroplasty.

BACKGROUND: Patellofemoral arthroplasty (PFA) is an alternative to total knee arthroplasty (TKA) for the treatment of patellofemoral arthritis. Although PFA may preserve native kinematics and accelerate recovery, it has been associated with higher revision rates. The purpose of this study is to compare complication rates and costs between PFA and TKA. METHODS: Using the PearlDiver database, 6,179 patients with isolated patellofemoral arthritis treated with PFA or TKA from 2010-2015 were retrospectively reviewed with 5-year follow up. PFA and TKA patients were matched by age, sex, and Elixhauser Comorbidity Index via a 1:1 stepwise algorithm. Five-year costs and complications were compared between matched cohorts. The lifetime costs of PFA and TKA were evaluated with Markov decision modeling. RESULTS: Compared to TKA, PFA was associated with fewer Emergency Department (ED) visits (6.1% vs 3.9%, p = 0.004) but a higher 5-year revision rate (9.9% vs 4.2%, p < 0.001). After multivariate regression, PFA was independently more likely to require revision (odds ratio 2.60, 95% confidence interval 1.32-4.71, p = 0.003). PFA was associated with lower total healthcare costs at every time point between 3 months ($18,014 vs $26,473, p < 0.001) and 5 years ($20,837 vs $27,942, p < 0.001). On average, the lifetime cost of PFA per patient was $5,235 less than for TKA ($26,343 vs $31,578). CONCLUSIONS: PFA is a less expensive alternative to TKA with a similar risk of medical complications but is associated with a significantly higher 5-year revision rate. Future studies should examine the reasons for PFA failure and methods to mitigate this risk.

Functional Outcomes, Survival Rate, and Complications of Patellofemoral Arthroplasty: Mid-Term Results From Independent Center.

Background Patellofemoral arthroplasty (PFA) is indicated for isolated patellofemoral arthritis. PFA is a less invasive, bone-preserving procedure with faster recovery when compared to total knee replacement. We aim to present the functional outcome, survival rate, and complications of PFA from our center. Methods A total of 45 consecutive PFA performed (mean age 58.02 ± 9.2 years; 34 females and 11 males; Avon prosthesis) during the study period was included. Prosthesis survivorship was measured using revision as the endpoint, and functional outcome was assessed using Oxford knee scores (OKSs), EQ-5D, and satisfaction scores. Postoperative complications, the number of revisions, and the reasons causing them were collected. Results The mean follow-up was 48.7 (range 16-66) months. As compared to preoperative scores, OKS and Eq5d showed significant improvements (p<0.001). The satisfaction scores indicated that 28 patients (62%) were very satisfied, 10 (26.7%) were satisfied, and seven (15.5%) were dissatisfied. Four patients (8.9%) underwent revision surgery with a total knee replacement. Out of four patients requiring revision, two had progressive arthritis of the medial compartment, one had aseptic loosening of the implants, and one had trauma. Five patients showed persistent anteromedial knee pain (12.2%); one patient had maltracking requiring lateral release; one patient developed stiffness with knee flexion less than 60 degrees requiring manipulation under anesthesia. Conclusion Our results indicated that good or excellent functional outcomes can be expected in >80% of patients with survivorship of 91.1% at mid-term. Careful patient selection and counseling should be done informing of the risk of dissatisfaction/persistent pain and revision surgery in the mid and long term. Long-term outcomes and factors determining good outcomes need to be evaluated in future research.

Flip Autograft Technique for Anterolateral Femoral Deficiency in Total Knee Arthroplasty.

Anterolateral bone loss of the femur within the trochlear groove presents a unique and rare issue in primary total knee arthroplasty (TKA). Unlike distal and posterior femur bone loss for which most contemporary TKA systems have modular augments, the same does not exist for anterolateral bone loss. We present a technique in which a patient's host bone from the standard distal femoral cuts was used to augment and provide a stable base for cementing of final femoral implants. Currently, the patient has 3-year follow-up with excellent results in terms of pain control with no evidence of component failure on the most recent radiographs. This technique provides a simple solution to a complex problem within primary TKA.

Medial/central PF arthritis and functionally stable ACL deficiency do not compromise outcomes of fixed-bearing medial UKA.

BACKGROUND: There is limited published data assessing functional scores and patient satisfaction following unicompartmental knee arthroplasty (UKA) in patients with patellofemoral (PF) arthritis or anterior cruciate ligament (ACL) deficiency. The purpose of this study was to determine whether medial/central PF arthritis or functionally stable ACL deficiency compromise outcomes of fixed-bearing medial UKA at a minimum follow-up of 2 years. The hypothesis was that equivalent outcomes can be achieved in patients with substantial medial/central PF arthritis or with functionally stable ACL deficiency. METHODS: The authors studied a consecutive series of 229 patients (240 knees) at 36.9 ± 6.3 months after receiving fixed-bearing medial UKA. Patients completed pre- and post-operative (2 years) clinical outcome questionnaires for Oxford Knee Score (OKS), EQ-5D, Knee injury and Osteoarthritis Outcome Score Physical Function Short Form (KOOS-PS), University of California, Los Angeles (UCLA) activity score, and Forgotten Joint Score (FJS). Multivariable analyses were performed to determine associations between clinical scores, patient demographics, PF arthritis and functionally stable ACL deficiency. RESULTS: Of the 240 knees, 125 (54%) had substantial medial/central PF arthritis and 21 (9%) functionally stable ACL deficiency. Multivariable analyses revealed no association between outcomes and medial/central PF arthritis, but knees with functionally stable ACL deficiency were associated with better KOOS-PS (ß = 8.99, p = 0.012). CONCLUSION: Fixed-bearing medial UKA grants satisfactory outcomes at 2 years even in knees with substantial medial/central PF arthritis or functionally stable ACL deficiency. Longer-term prospective studies with larger cohorts are needed to confirm these promising findings regarding outcomes in patients traditionally contraindicated for medial UKA.

Treatment Options for Patellofemoral Arthritis.

PURPOSE OF REVIEW: To present a synthesis of recent literature regarding the treatment of patellofemoral arthritis RECENT FINDINGS: Risk factors of PFJ OA include patella malalignment or maltracking, injury to supportive structures including the MPFL, dysfunction of hamstring and quadriceps coordination, lower limb alignment, trochlear dysplasia, patellar trauma, or ACL surgery. Special physical exam maneuvers include patellar grind test, apprehension test, and lateral patellar tilt angle. Radiographs that should be obtained first-line include weight bearing bilateral AP, lateral, and Merchant views. CT and MRI are used to assess trochlear dysplasia, excessive patellar height, and TT-TG distance. Non-operative management options discussed include non-pharmacologic treatment (patient education, self-management, physical therapy, weight loss), ESWT, cold therapy, taping, bracing, and orthotics. Pharmacologic management options discussed include NSAIDs, acetaminophen, oral narcotics, and duloxetine. Injection therapies include glucocorticoids, hyaluronic acid, PRP, and other regenerative therapies (BMAC, adipose, or mesenchymal stem cells). Other treatment options include radiofrequency ablation and botulinum toxin. The algorithm for the surgical treatment of PFJ OA can begin with arthroscopic assessment of the PF articular cartilage to address mechanical symptoms and to evaluate/treat lateral soft tissue with or without overhanging lateral osteophytes. If patients fail to have symptomatic improvement, a TTO can be considered in those patients less than 50 years of age or active patients >50 years old. In patients with severe PFJ OA, refractory to the above treatments, PFA should be considered. While early PFA design and technique were less than encouraging, more recent implant design and surgical technique have demonstrated robust results in the literature. Patellofemoral osteoarthritis is a challenging orthopedic problem to treat, in that it can often affect younger patients, with otherwise well-functioning knees. It is a unique entity compared to TF OA with distinct epidemiology, biomechanics and risk factors and treatment options.

Midterm results of modern patellofemoral arthroplasty versus total knee arthroplasty for isolated patellofemoral arthritis: systematic review and meta-analysis of comparative studies.

BACKGROUND: Both Patellofemoral Arthroplasty (PFA) and Total Knee Arthroplasty (TKA) are accepted surgical options for end-stage isolated patellofemoral osteoarthritis (PFOA). We performed a systematic review and meta-analysis to compare outcomes of PFA and TKA by evaluation of the patient-reported outcome measures (PROMs). METHODS: We systematically identified publications reporting on patients that underwent either TKA or modern PFA for isolated PFOA. Meta-analysis software was used to screen for potential articles with at least two years' follow-up. Data were extracted and analysed for all PROMs operating time, postoperative inpatient time, complications and cost. We included five studies in our cumulative meta-analysis and reviewed them using Review Manager V.5.0. We computed the risk ratio as a measure of the treatment effect, taking into account heterogeneity. We used random-effect models. RESULTS: No significant difference was found between both TKA and PFA in the context of operating time. No significant difference after five years' follow-up was found between the two treatment options in terms of UCLA score and patient satisfaction. PFA showed significant improvement in WOMAC score at five-year follow-up, less postoperative inpatient time, better cost-effectiveness and significantly less blood loss. CONCLUSION: PFA seems to be a viable alternative to TKA for treatment of isolated PFOA in appropriately selected patients. PFA showed less postoperative inpatient time and blood loss with similar PROMs to the TKA. Moreover, it is an economically beneficial joint-preserving procedure.

Patellofemoral joint degeneration: A review of current management.

The patellofemoral component of the knee joint is affected by a wide range of degenerative causes without involving the other parts of the knee. It is often the presenting pathology in early knee osteoarthritis and missed due to a variable presentation. Accurate examination and focused investigation can help with early diagnosis and guide treatment. Various aspects to treatment need to be addressed after thorough evaluation. Guidelines to approach the multifactorial pathology of the patello-femoral joint are provided with focus on the degenerative component of disease.

Older age and varus alignment lead to early failure in treating patellofemoral osteoarthritis with Fulkerson osteotomy.

Background: It is unclear the risk factors for the failure of modified Fulkerson osteotomy. Methods: We retrospectively reviewed 40 patients who underwent the modified Fulkerson osteotomy from 1998 to 2015. There were 4 males and 36 females. The mean age of the study group was 50.2 ± 11.2 years. We used standard anteriorization measuring 10-15 mm and medialization measuring 10 mm while maintaining an intact periosteal sleeve. Results: Both the patellofemoral angle and the congruence angle improved significantly after 5.9 years. Preoperatively, the mean preoperative Lysholm score was 56.12, and the Knee Society score was 60.52. At the final follow-up, these scores improved significantly to 88.75 and 86.49, respectively. However, eight patients (20%) underwent total knee arthroplasty in the follow-up period, five of whom underwent the operation within 5 years. Comparing the survival and non-survival groups, there was a significant difference of an older age in the TKA conversion group (survival: 48.3 ± 11.1; non-survival: 57.8 ± 8.7, p = 0.03). For knee alignment, the non-survival group had a mean valgus femorotibial angle of 1.8° ± 4.9° preoperatively, and the survival group had a mean valgus angle of 6.4° ± 4.5° (p = 0.03). Conclusions: we found that patients with older age and those with varus alignment have an increased risk of deteriorated medial femorotibial cartilage.

Dysplastic Patellofemoral Joints Lead to a Shift in Contact Forces: A 3D-Printed Cadaveric Model.

BACKGROUND: The distribution of contact forces across the dysplastic patellofemoral joint has not been adequately quantified because models cannot easily mimic the dysplasia of both the trochlea and the patella. Thus, the mechanical consequences of surgical treatments to correct dysplasia cannot be established. PURPOSE/HYPOTHESIS: The objective of this study was to quantify the contact mechanics and kinematics of normal, mild, and severely dysplastic patellofemoral joints using synthetic mimics of the articulating surfaces on cadavers. We tested the hypothesis that severely dysplastic joints would result in significantly increased patellofemoral contact forces and abnormal kinematics. STUDY DESIGN: Controlled laboratory study. METHOD: Patellofemoral dysplasia was simulated in 9 cadaveric knees by replacing the native patellar and trochlear surfaces with synthetic patellar and trochlear implants. For each knee, 3 synthetic surface geometries (normal, showing no signs of dysplasia; mild, exemplifying Dejour type A; and severe, exemplifying Dejour type B) were randomized for implantation and testing. Patellar kinematics and the sum of forces acting on the medial and lateral patellar facets were computed for each knee and for each condition at 10° increments from 0° to 70° of flexion. RESULTS: A pronounced lateral shift in the weighted center of contact of the lateral facet occurred for severely dysplastic knees from 20° to 70° of flexion. Compared with normal geometries, lateral patellar facet forces exhibited a significant increase only with mild dysplasia from 50° to 70° of flexion and with severe dysplasia at 70° of flexion. No measurable differences in medial patellar facet mechanics or joint kinematics occurred. CONCLUSION: Our hypothesis was rejected: Severely dysplastic joints did not result in significantly increased patellofemoral contact forces and abnormal kinematics in our cadaveric simulation. Rather, severe dysplasia resulted in a pronounced lateral shift in contact forces across the lateral patellar facet, while changes in kinematics and the magnitude of contact forces were not significant. CLINICAL RELEVANCE: Including dysplasia of both the patella and trochlea is required to fully capture the mechanics of this complex joint. The pronounced lateralization of contact force in severely dysplastic patellofemoral joints should be considered to avoid cartilage overload with surgical manipulation.

Operative Treatment Options for Patellofemoral Arthritis: An Expert Recommendation of the AGA Patellofemoral Committee.

BACKGROUND: The operative therapy of patellofemoral arthritis requires an individual approach depending on the underlying injury. However, the literature lacks recommendations for its course of action. PURPOSE: To generate an expert recommendation of therapy for different patellofemoral abnormalities in patients suffering from isolated patellofemoral arthritis. STUDY DESIGN: Consensus statement. METHODS: To generate recommendations, the AGA Patellofemoral Committee performed a consensus process using the Delphi method based on the available literature on isolated patellofemoral arthritis. RESULTS: In most statements and recommendations, a high percentage of consensus could be found. However, also in the expert group of the AGA Patellofemoral Committee, some controversies on the treatment of patellofemoral arthritis exist. CONCLUSION: The operative therapy of isolated patellofemoral arthritis is a challenging topic that leads to controversial discussions, even in an expert group. With this consensus statement of the AGA Patellofemoral Committee, recommendations on different operative treatment options were able to be generated, which should be considered in clinical practice.

Has the modern design of Attune total knee replacement improved outcome in patients with isolated patellofemoral arthritis?

INTRODUCTION AND AIM: Modern knee replacements aim to improve patient function in arthritis affecting different compartments of the knee. This study evaluates the Patient Reported Outcome Measure (PROM) and functional outcome of a modern total knee replacement (Attune, DePuy) in patients with isolated patellofemoral arthritis. METHODS: A total of 50 consecutive patients with isolated unilateral patellofemoral arthritis having had Attune total knee replacements at a single institution between 2010 and 2016 were prospectively studied. Five patients who developed symptoms on the opposite side during the study and two patients lost to follow-up were excluded. One patient needed early revision for loosening, leaving a total of 42 patients to be followed up over a period of 4 years. The Oxford Knee score (OKS) and Knee Injury and Osteoarthritis Outcome Score (KOOS) recorded pre-operatively and at follow-up was compared. A Functional assessment at around 8 months after operation was undertaken. RESULTS: At average follow-up of 24 months the mean OKS score improved by 15 points and the KOOS score improved by 20 points. Final KOOS sub-score for Pain was 80, Symptom 80, and ADL 82, Sports & Recreation 32 and QOL 60. Functional assessment at mean 8 months showed that a significant number of patients were able to Kneel (50%); Sit cross legged (23%); sit on their heel (23%) and were able do a single leg dip test (86%). CONCLUSION: This unique study of a modern design total knee replacement (Attune) in patients with isolated unilateral patellofemoral arthritis shows good PROM scores at 2 years and good functional assessment results at 8 months. The PROM scores are marginally better than the published results with Attune's predecessor, in a similar cohort of patients, but falls short of the published results of patellofemoral replacement implants. Large randomised comparative studies between traditional and the modern implant design is recommended to answer the question if design modification has influenced clinical outcome in patients with patellofemoral arthritis.

The midterm results of a cohort study of patellofemoral arthroplasty from a non-designer centre using an asymmetric trochlear prosthesis.

PURPOSE: Patellofemoral arthroplasty (PFA) prosthesis with asymmetric trochlear component was introduced as an improvement from existing designs for surgical treatment of symptomatic isolated patellofemoral arthritis. The purpose of this study was to evaluate midterm results in patients who underwent PFA procedure using such prosthesis. METHODS: Our study involved a continuous retrospective cohort of patients who underwent PFA using Journey PFA prosthesis with an asymmetric trochlear component, performed between June 2007 and July 2016 at a non-designer centre. The Patient Reported Outcome Measures and patient satisfaction questionnaires were collected for final evaluation. RESULTS: A total of 103 PFA performed on 79 patients were evaluated. Median age at the time of surgery was 58years (range 42 to 78years); the mean follow-up period was 6 years (range 2 to 11years). Four knees were revised to Total Knee Arthroplasty for reasons not related to the implant. The cumulative survival estimated by the Kaplan-Meier method was 94.3% (95% confidence interval: 88.4%-100%). There were statistically significant improvements in functional outcome scores. CONCLUSION: This series of patients who underwent PFA with the asymmetric trochlear component has shown promising mid-term results with no implant-related complications.